I can display images in a tableview but can't transfer the application on to the iPhone. I am obviously not releasing some memory but can't figure out what. I have approx 30 pix that are each 250k in size. I have tried storing the images in SQLite as well as the filesystem and get the same problem for both; works in the simulator but does not get to the iDevice (touch actually).
Suggestions?
Check your images are in 24bit format if they are PNGs
I think the problem is to do with image formats - not a lot else makes sense.
What do you mean by they are in a tableview - is this relevant? Can you see them when they are not in a tableview?
No Sample code to review, but have made sure that your not allocating or holding the images more than once. 30 pics at 250k is 7.5MB plus the code, so that app starts off hefty. If the images are not being released, the size could be sending Memory Warnings. Do you have an NSLog("Warning Message"); in your application's - (void)didReceiveMemoryWarning {..} Try setting one if not and then run app in the Simulator with the Console open and double check that MEMORY is not your problem. If that NSLog gets triggered you know that is where the problem is.
I think its too much for the tableview to show this big images on the iPhone. And if it would work you would also have a problem with scrolling performance in the tableview.
Related
So when I run the application from the device the pictures show up and everything works great. However, when I move to the device I run in about 10 out of 38 pictures that don't show up. I am pulling the names for the images from an sqlite database and I already checked and the names are correct, case and everything. I checked the bundle and the images are correctly in there.
Does memory play into effect in this? I am not really sure what else could cause this to happen??
Thanks!
Solution:
The files somehow were not saved properly and were unable to be opened by say photoshop or paint even. So with the files not being able to be open they weren't showing up... Thanks for the help everyone!
First thing to check is the case of the strings you're using to refer to the resources. The iPhone is case sensitive, but the simulator is not.
Oops, just seen that you checked the case. Better log all your UIImage creation calls then!
The simulator accepts a wider range of image formats. Sometimes you had a specific file type that the device cannot display. Double check the 10 files looking for some difference from the others ones.
Yes, memory absolutely plays into this. Check your UIImage creation calls and make sure they dont return empty. Also, check to see if youre getting memory warnings in the console window.
Generally, if in-memory size was the culprit, your application would crash with a low memory error on the device. However, it seems like the images just don't display.
One other thing that can be going wrong is the size of the images. UIViews on the iPhone can only have dimensions smaller than the maximum texture size supported by the GPU. Apple states that this is 1024 x 1024, but I've found it to be more like 2048 x 2048 on even the original model iPhone. You may be creating a view for some of these images that exceeds this size in one dimension, but your Mac has a larger maximum texture size on its GPU and so it displays fine in the Simulator.
Apparently the iPhone caches the launch screens. So in my case, I had to reboot my iPhone before being able to see the image.
I have an iPhone app that, among other things, allows users to store photos. When a new photo is added to the app's data store, I cache a thumbnail version of the image so that the photo thumbnail grids load in a reasonable amount of time.
The problem is that these thumbnails look great on a pre-Retina Display screen, but they look a little blurry on RD displays. It's not so bad that the images are unusable, but I would really like to be able to get the full benefit of Retina Display for images users saved with older versions of my app.
The problem is that re-creating all these thumbnails takes way too long. In my tests, it took about a minute and a half to re-encode a sample database to high-res thumbnails (admittedly a large one) on my iPhone 4. It will be even worse on older hardware.
How can I get around this? Doing a one-time migration seems out of the question, given the performance results above. Other options are shrinking the thumbnails lazily (i.e. as they're displayed on-screen) and then saving them to the database at that point. Screens full of old images will be sluggish the first time they're viewed, and then snappier after that.
Are there other approaches to consider? Anyone else faced this problem?
I dont like the idea that you try and convert the images.
User will quickly get impatient and say you app is buggy and takes ages to load.
I think you solve the situation without any re-processing of full sized images.
On older hardware you would not have a retina display (so no need to upsize the images). If they have a retina display then they have a fast iPhone iPod.
I would suggest you graphically solve the problem by how you display the thumbnail images. so instead of fullscreen put a border around this image and show it at its true resolution (dont upscale it). Or show 4 images where you normally show 1 (since iPhone screen is 4x the resolution).
Instead of resampling the original massive image, you could do a bicubic upsample of the thumbnail making it 4x the size. This will make it slightly blurry but it should look better than the iPhone scaling which will look really bad. The upsample would be ultra fast as its working with a small image.
I cannot help you out on upsampling but there will be some code somewhere.
Cheers, John.
Screens full of old images will be sluggish the first time they're viewed, and then snappier after that.
It doesn't have to be sluggish.
It's a bit of a pain, but you can do most of your processing in a background thread. Set the thread priority to something low (like 0.1) to avoid making the UI too slow. The easiest way to do this is to set up an NSOperation for each image you need to convert and add them to a NSOperationQueue with maxConcurrentOperationCount=1.
If writes are not atomic, in -applicationDidEnterBackground: or -applicationWillTerminate: (or in something listening for the corresponding notifications notifications), do something like [queue cancelAllOperations]; for (NSOperation * operation in queue) { [operation setThreadPriority:1]; } [queue waitUntilAllOperationsAreFinished];; you get about 10 seconds or so which should be enough for the image conversion to finish writing to disk (and thus avoid half-written files). For added protection, check [operation isCancelled] immediately before the write if it might take longer than 10 seconds. Obviously, in -applicationWillEnterForeground:, you should restart the conversion (remembering that some of the images have already been converted).
Concurrency issues are fun to track down...
(Note that [data writeToFile:path atomically:YES] isn't sufficient — it's likely to leave temporary files lying around if the app is killed during the write. I'd recommend storing thumbnails in Core Data if you can, but that might be out of the question for existing apps.)
I'm seeing my app being killed by iOS with an out of memory message, however, while tracing the progress of the app in the Allocations Instrument, I see lots of mallocs that seem to be occurring outside of the code I've written.
I'm not seeing any leaks being caught, so I assume these allocations are supposed to be there. Thing is, because I'm not sure about why they have been allocated, I'm not sure what I can do to optimize the app and prevent the OS from jettisoning my app.
Does anyone know why the memory is being allocated, or is there any way for me to find out?
Here are a couple of shots from Instruments showing the mallocs. In the second shot, all of the allocations have the same stack trace.
EDIT
I' displaying a single large image as the UIView background (1024x768), then overlaying a smaller (600px square) UIView with some custom drawing and a third UIView (550px square) over the top of those that contains two 550px square images overlayed.
I'm guessing that this is not appropriate, and there is probably a better way of achieving the composition of views I need for the app to work.
Should this be possible on the iPad?
I think there's not really much information to go on here - if you add a bit more information about what this view in your app is doing you might get some more informed suggestions.
From the screenshot, it would appears large blocks are being allocated to display an image.
Given that I'd hazard a guess that either you're trying to display some very large images, or you UIView is large, or you have more UIViews in memory that you need to display the current screen.
I guess the easiest way to track down exactly where they're coming from would be to disable the part of the application you suspect then run again and see if the allocations still occur.
EDIT
Are all the images the same size as you're displaying them? (ie. are you trying to display a 5M photo as the 1024x768 background?) If not you probably need to scale them down to the size you are display them, or at least closer.
If you're not needing transparency, make sure to make all the views opaque.
I figured out the source of the problem - I was using
[UIImage imageNamed:#'Someimage']
to load in my images. This, as I'm sure many people are aware, caches the image data. I had enough images of sufficient size to cause my app to be jettisoned.
The problem was apparent not because of the size of the image but because of both the size and number of images I was using. The lesson here is be careful with [UIImage imageNamed:].
Thanks for all of the help, chaps!
Mallocs can occur inside of other API's that your app calls (such as loading images, views, playing long sounds, etc.) You can try changing the size of your images, views, sounds and other objects by various amounts as a test, and see if the size of the malloc'd memory changes track one of the changes that you've made.
i am developing a app which contains feature like default photo browser in iphone. I done some what similar to that. but after loading some(near about 10-15) images from remote server,i am receiving memory warning.My requirement is loading image one by one. For this, on scroll view i am putting an images and increasing the contentSize of scroll view. it will work fine. but due to memory warning app quite.
Guys, any have any idea to approach for this feature which work similar to photo app without problem?
thanks in advance .
You're running out of memory because you're keeping the data for 10 or more images in memory at one time. You need to have more logic in your code that not only preloads and increases the scroll view's content size, but also removes UIImageViews from the scrollview (and thus from memory) as the user scrolls to newer stuff. (You can also save "evicted" images to the cache area on disk so if the users scrolls back you don't have to go to the server again.)
If you use a UITableView, it will request the images only when needed, and will automatically purge off-screen cells to save memory. It may not fit into the aesthetic for your application, though.
My application contains more than 200 images each with size approx. 15 KB. I want to flip these image one by one. Is there will be any time lag for loading images? Is there any alternate method for doing that?
Anyone please help!
My application contains more than 200 images each with size approx. 15 KB. I want to flip these image one by one.
OK.
Is there will be any time lag for loading images?
Maybe. Try it and see. If there is, run your app under Instruments to see what really caused it.
Is there any alternate method for doing that?
You haven't proposed a primary method to be alternate to.
The main thing is that, since this is an iPhone app, you're probably not going to need 200 images loaded at once. Consider the Home screen: Those icons are about as small as is practical, and there are only 20 (24 on the iPad) of them on the screen at one time.
Assuming you want to allow scrolling or paging through the list, you'll probably want to keep a pageful up and a pageful down already loaded and flipped and ready to display, to make scrolling/paging faster. That's still only 60–72 images, and you can do half to two-thirds of them after displaying the visible 20–36.
Moreover, are the images always flipped? If so, then flip them at build time and copy the flipped images into your app, and do no flips at runtime. Then you're just displaying images.